Apple has released Logic Pro 9.1 and Main Stage 2.1 via their Software Update utility and website. According to the company, these updates deliver improved compatibility and numerous fixes. They also bring support for a 64-bit native mode and compatibility with 64-bit Audio Unit plug-ins, which is really the big news here. Logic 9.1 weighs in at 191.14MB and requires Mac OS X 10.5.7 or later for 32-bit mode, or 10.6.2 or later for 64-bit mode. Main Stage 2.1 weighs in at 210.91MB and requires the same for each mode.